This invention relates to a class of antiperspirant salts that may be used to formulate antiperspirants with enhanced efficacy.
A variety of art is available that describes various salts and methods of making them. U.S. Pat. No. 4,331,609 to Orr teaches an antiperspirant active comprising aluminum and zirconium made with separate aluminum and zirconium compounds as well as a neutral amino acid wherein the molar ratio of neutral amino acid to total metal is from about 0.90 to about 0.24. The total metal:chlorine ratio in the complex that is formed is less than 1.30.
EP publication number 0 047 650 describes aqueous solution-stable antiperspirant complexes comprising an aluminum compound, a zirconium or hafnium compound, a water soluble neutral amino acid and an inorganic acid. The molar ratio of neutral amino acid to total metal is from about 0.90 to about 0.24 in an aqueous system, and the molar ratio of neutral amino acid to total metal is from about 0.90 to about 0.75 in a non-aqueous system. The total metal:chlorine ratio in the complex that is formed is less than 1.30.
United Kingdom Patent Application GB 2,076,289 describes an antiperspirant compositions comprising a combination of an aluminum chloride and an aluminum zirconium hydroxychloride in a synergistic mixture. The metal:chloride ratio is less than 0.9.
Canadian Patent 1,153,313 describes an antiperspirant composition which contains a buffering agent such as glycine with a synergistic mixture of aluminum chlorohydrate, aluminum chloride or aluminum zirconium polychlorohydrate complex. The molar ratio of aluminum to chloride is in the range of 0.78:1 to abut 1.95:1. Various salts are described which have a metal:halide ratio of 2.1:1-0.9:1. The glycine:zirconium ratio is much less than 1:1.
U.S. Pat. No. 4,871,525 to Giovanniello et al describes a solid powder of aluminum zirconium hydroxyl halide glycinate complex having improved antiperspirant activity wherein the glycine is used to prevent gel formation. The ratio of Zr to glycine is less than 1:1.
U.S. Pat. No. 6,126,928 to Swaile describes antiperspirant compositions wherein the molar ratio of neutral amino acid to total metal (aluminumxe2x80xa2zirconium) is from about 0.90 to about 0.24, and the mole ratio of (aluminumxe2x80xa2zirconium):chlorine is less than about 1.30:1.
U.S. Pat. No. 6,066,314 to Tang describes the use of post added glycine to aluminum zirconium salts in an amount in the range of 1:1.2-1:5 of zirconium:amino acid on a weight:weight basis.
None of the above cases described the combination of metal to chloride in combination with the glycine to zirconium ratio as found in the instant invention. Thus, it is surprising that the antiperspirant actives described in this invention provide more efficacious cosmetic products.
This invention comprises aluminum zirconium salts which have a metal to chloride molar ratio in the range of 0.9-1.2:1 and a glycine:zirconium molar ratio greater than 1.3:1, particularly greater than 1.4:1.
This invention comprises an aluminum zirconium tetrachlorohydrex glycine salt having a metal to chloride ratio in the range of 0.9-1.2:1 (especially in the range of 0.9-1.1:1 and, more particularly in the range of 0.9-1.0:1); and a glycine:zirconium ratio greater than 1.3:1, particularly greater than 1.4:1.
The salts of this invention may be made in a variety of ways:
Method A:
An aluminum chlorohydrate (ACH) solution of ACH salt in water of suitable concentration is mixed with an aqueous solution of zirconyl chloride (ZrOCl2) of suitable concentration and powdered glycine. The mixture is stirred at room temperature to obtain the salt.
Method B:
A suitable commercially available aluminum zirconium tetrachlorohydrex glycine salt is obtained and mixed with a sufficient amount of an aqueous aluminum chloride (AlCl3) solution and powdered glycine. The mixture is stirred at room temperature to obtain the salt.
When Method B is used, a suitable salt to use as a starting material includes various types of tetra salts such as aluminum zirconium tetrachlorohydrex gly, aluminum zirconium tetrachlorohydrex gly propylene glycol complex aluminum zirconium tetrachlorohydrex gly dipropylene glycol complex, and mixtures of any of the foregoing.
Method C:
An aqueous aluminum chlorohydrate (ACH) solution made from an activated ACH salt of suitable concentration is mixed with an aqueous solution of zirconyl chloride (ZrOCl2) of suitable concentration and powdered glycine. The mixture is stirred at room temperature for a short period of time and then spray dried to obtain the salt in powder form.
If the product is used as a solid powder, the size of the particles of antiperspirant active of the invention currently does not appear to be critical and may include conventional sizes such as greater than 2 to 100 microns, with selected grades having an average particle size of 30-40 microns; finer sized grades having an average particle size distribution from 2-10 microns with average size of about 7 microns as made by a dry-grinding method; and micronized grades of the type described in a co-pending patent application U.S. Ser. No. 9/579,322 having an average particle size of less than or equal to 2 microns, particularly less than or equal to 1.5 microns.
The enhanced salts of this invention may be used to formulate antiperspirants having improved efficacy. Such antiperspirants include solids such as sticks and creams (creams sometimes being included in the term xe2x80x9csoft solidxe2x80x9d), gels, liquids (such as are suitable for roll-on products), and aerosols. The forms of these products may be suspensions or emulsions.
It is preferred that the glycol content of the formulations be kept to a minimum.
Examples of suitable formulations include the following.
Sticks
Stick products may be made with conventional gelling agents such as stearyl alcohol and dibenzylidene sorbitol. A sample formulation is as follows:
40-55% (particularly 45%) cyclomethicone (especially D5 cyclomethicone)
20-30% (particularly 21%) stearyl alcohol
7-15% (particularly 10%) talc
15-22% (particularly 22%) antiperspirant active in powder form
1-3% (particularly 2%) fragrance
Roll-Ons
45-65% (particularly 55%) cyclomethicone (especially D5 cyclomethicone)
0.1-10% (particularly 3%) cyclomethicone/dimethicone copolyol (such as Dow Corning 2-5185 C)
10-25% (particularly 20%) antiperspirant active in solution form (25-45% actives on an anhydrous basis in water)
5-30% (particularly 20%) water
1-3% (particularly 2%) fragrance
Soft solids
Soft solids may be made with formulations described in co-pending patent application (U.S. Ser. No. 9/273,152 and PCT Publication number WO 99/51192. A sample formulation is as follows:
40-70% (particularly 50%) elastomer in cyclomethicone (KSG-15 from Shin-Etsu)
5-15% (particularly 6%) polyethylene (for example, beads having a density in the range of 0.91-0.98 g/cm3 and an average particle size in the range of 5-40 microns)
10-20% (particularly 15%) C12-15 alkylbenzoate (Finsolv TN from Finetex)
0.1-25%% (particularly 22%) antiperspirant active in powder form
1-15% (particularly 5%) dimethicone (100 centistokes)
1-3% (particularly 2%) fragrance
Gels
Gels may be made with a variety of formulations such as
5-50% (particularly 29%) cyclomethicone (particularly D5)
0.1-10% (particularly 3%) cyclomethicone/dimethicone copolyol (such as Dow Corning 2-5185 C)
0-10% (particularly 5%) hydrogenated polyisobutene 250
0-10% (particularly 5%) C12-15 alkylbenzoate (Finsolv TN from Finetex)
0-10% (particularly 5%) dimethicone (100 centistokes)
0.1-25% (particularly 20%) antiperspirant active in powder form or 10-25% (particularly 20%) of active in solution (25-45% actives on an anhydrous basis)
5-50% (particularly 30%) water
1-3% (particularly 2%) fragrance
Note that in the explanation of the invention, where water is listed it is intended to count the contribution of the water present in the antiperspirant solution as part of the overall water content. Thus, water is sometimes listed as part of the actives solution or sometimes listed separately.
In a preferred embodiment the refractive indices of the external and internal phases are matched within 0.005 to obtain a clear product.
Particular formulations of interest include:
Formulation A:
0.5-2.5% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
55-65% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
1-10% PPG-3 myristyl ether
10-25% antiperspirant active of the invention
10-25% water
0.5-1.5% fragrance
Formulation B
1.0-3.0% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
40-60% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
1-5% cyclomethicone (in addition to that found in the elastomer)
4-12% PPG-3 myristyl ether
15-30% antiperspirant active of the invention
15-35% water
0.5-1.5% fragrance
Formulation C
1.0-3.0% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
1-10% hydrogenated polyisobutene (for example, Fancol(trademark) Polyiso 250)
40-55% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
3-8% PPG-3 myristyl ether
15-20% antiperspirant active of the invention 20-30% water
1.0-3.0% fragrance
Formulation D
1.0-3.0% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
40-60% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
3-8% PPG-3 myristyl ether
15-30% antiperspirant active of the invention
15-30% water
0.5-1.5% fragrance
1-10% diethylhexyl naphthalate
Formulation E
0.5-2.5% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
60-70% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
7-10% antiperspirant active of the invention
25-35% water
1-10% methylpropylene diol (MPDiol)
0.5-1.5% fragrance
Formulation F
1.0-3.0% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
6-10% hydrogenated polyisobutene (for example, Fancol(trademark) Polyiso 250)
35-45% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
6-10% PPG-3 myristyl ether
40-50% antiperspirant active of the invention as 43% active in water
no additional water
0.5-1.0% fragrance
Formulation G
0.1-0.6% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
4-7% hydrogenated polyisobutene (for example, Fancol(trademark) Polyiso 250)
40-50% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
4-7% PPG-3 myristyl ether
40-50% antiperspirant active of the invention as 43% active in water
no additional water
0.5-1.0% fragrance
Formulation H
0.5-2.0% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
1-7% hydrogenated polyisobutene (for example, Fancol(trademark) Polyiso 250)
40-50% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
45-55% antiperspirant active as 43% active of the invention in water
no additional water
0.5-1.5% fragrance
Formulation I
2-7% dimethicone copolyol (for example, Dow Corning 2-5185C (48%))
0.1-1% Oleath-20
1-5% C12-15 alkyl benzoate (Finsolv TN)
15-25% elastomer in cyclomethicone (for example, DC-9040 from Dow Corning Corporation (Midland, Mich.) or KSG-15 from Shin-Etsu Silicones of America (Akron, Ohio))
15-25% antiperspirant active
15-30% water
0.5-1.5% fragrance
The cosmetic composition according to the present invention can be packaged in conventional containers, using conventional techniques. Where a gel, cream or soft-solid cosmetic composition is produced, the composition can be introduced into a dispensing package (for example, conventional packages for gels with glide on applicators, jars where the gel or cream is applied by hand, and newer style packages having a top surface with pores) as conventionally done in the art. Thereafter, the product can be dispensed from the dispensing package as conventionally done in the art, to deposit the active material, for example, on the skin. For sticks, sprays, aerosols and roll-ons the compositions can be placed in a conventional types of container (with the inclusion of propellants in aerosols). This provides good deposition of the active material on the skin.
Compositions of the present invention can be formulated as clear, translucent or opaque products, although clear products are preferred. A desired feature of the present invention is that a clear, or transparent, cosmetic composition, (for example, a clear or transparent deodorant or antiperspirant composition) can be provided. The term clear or transparent according to the present invention is intended to connote its usual dictionary definition; thus, a clear liquid or gel antiperspirant composition of the present invention allows ready viewing of objects behind it. By contrast, a translucent composition, although allowing light to pass through, causes the light to be scattered so that it will be impossible to see clearly objects behind the translucent composition. An opaque composition does not allow light to pass therethrough. Within the context of the present invention, a gel or stick is deemed to be transparent or clear if the maximum transmittance of light of any wavelength in the range 400-800 nm through a sample 1 cm thick is at least 35%, preferably at least 50%. The gel or liquid is deemed translucent if the maximum transmittance of such light through the sample is between 2% and less than 35%. A gel or liquid is deemed opaque if the maximum transmittance of light is less than 2%. The transmittance can be measured by placing a sample of the aforementioned thickness into a light beam of a spectrophotometer whose working range includes the visible spectrum, such as a Bausch and Lomb Spectronic 88 Spectrophotometer. As to this definition of clear, see European Patent Application Publication No. 291,334 A2. Thus, according to the present invention, there are differences between transparent (clear), translucent and opaque compositions.
The improved efficacy can be evaluated by reference to conductivity tests.
The release of antiperspirant actives into the sweat is a significant event in the development of an antiperspirant effect. The magnitude of the antiperspirant effect is related to the concentration of the antiperspirant salt in the sweat, and therefore measuring the concentration of antiperspirant salt can provide an estimate of antiperspirant efficacy. A variety of methods can be used to evaluate antiperspirant salt concentration, ranging from atomic absorption, ICP, and HPLC to solution conductance of aqueous films. The later method is especially well suited for measuring the release of small amounts of antiperspirant salts. The methods outlined below use solution conductance to estimate antiperspirant salt release upon short exposures to deionized water.
As noted above, the conductance of the compositions of the invention is defined with reference to a value of at least 250 micro Siemens/cm/ml when the composition is loaded with at least 7% of an antiperspirant active (such as the antiperspirant actives listed above) and when the conductance is measured by a fixed geometry test. For purposes of clarification it should be explained that there are a variety of tests and test conditions that can be used to evaluate:
(1) xe2x80x9cConductancexe2x80x9d is defined as an absolute measure of current flow through a solution with the dimensions of micro Siemens/cm, which value is independent of probe geometry. This value is divided by the volume (in ml) of applied water to give the conductance number with the units of micro Siemens/cm/ml. This test is deemed a more reproducible measurement since it references a set of fixed dimensions and units.
(2) Alternatively, xe2x80x9cconductivityxe2x80x9d as a measure of current flow through a solution without reference to probe geometry, and which is measured in micro Siemens. This test is convenient for quick screening of solutions.
Standard Test for Thin Film Conductivity
One test for conductivity is called herein the xe2x80x9cstandardxe2x80x9d test. A non-conducting plastic block (for example, made from PLEXIGLAS(copyright) material) to form an oval shaped well 12.2 cmxc3x972.5 cm with a depth of 100 microns. This depth corresponds to the mean thickness of an antiperspirant product applied to the underarm of a human person during real use conditions (approximately 50 to 100 microns). An aliquot of test sample is placed in the well of the block sufficient to fill the well to the brim. Excess sample is scraped off by running a flat edged instrument over the surface of the block. The sample block, with the product film, is then either (a) equilibrated at room temperature for two hours or (b) placed in a synthetic underarm to simulate in vivo conditions. If method (b) is used, the air temperature inside the synthetic underarm is maintained at 33 to 35xc2x0 C. and a relative humidity of 85 to 95%, and the sample blocks are placed on a temperature controlled surface maintained at body temperature (37xc2x0 C.). These conditions closely approximate the temperature gradients normally found in the underarm. Samples are equilibrated in either the (a) or (b) environments for two hours prior to measurement of antiperspirant salt release by solution conductivity. After two hours the sample blocks are removed from the controlled environment and placed on a stage for conductivity measurement. An aliquot of 250 microliters of water with a resistance of at least 17 mega ohms is placed on the surface of the sample film, and the conductance of the water is measured as a function of time with a Skicon 200 Skin surface Hygrometer (I.B.S. Co., Ltd., Shizuoka-ken, 430, Japan) using an Elsnau (MT-8C Probe) electrode (Todd Maibach and Associates, San Francisco, Calif.). The electrode is positioned so that it touches the bottom of the test sample in the well. Conductivity is measured in micro Siemens at 3.5 MHz. Data is collected at 0.1 sec intervals for approximately 100 sec. Solution conductivity after 10 seconds of exposure to the water is used to compare the release of active salt for different formulations. This method is believed to be particularly useful for evaluating the release of antiperspirant salts in the absence of other salts. The standard method is useful as a quick screening tool for active salt release studies. A solution conductivity of approximately 400 or greater micro Siemens at 10 sec after application of the water droplet to the surface of the test sample, can be considered evidence of significant release of the antiperspirant active salt from the film surface and correlates with improved antiperspirant efficacy.
Fixed Geometry Test for Thin Film Conductance
One of the limitations of the Standard Test is that the area of the water droplet is not controlled and, therefore, the apparent conductance (which is measured as conductivity because the water volume is not controlled) is dependent on droplet spreading. This will lead to an underestimate of the actual solution conductance (and therefore antiperspirant salt release), of water drops which spread significantly. In order to measure the absolute concentration of the antiperspirant salts the spreading of the water drop must be stopped. This can be accomplished by placing a well of know dimensions on the surface of the product film to establish an area of constant size that is exposed to the water droplet. A more predictable test is needed, such as the Fixed Geometry Test.
The Fixed Geometry Test uses the same basic technique as the Standard Test in terms of preparation of the test well, addition of the test sample and equilibration of the sample to a selected temperature. Instead of allowing the water to flow freely on the surface of the test film, however, a second structure of non-conducing plastic predrilled with holes of a fixed diameter is clamped over the well block. The second structure with holes is also made of a non-conducting material (such as PLEXIGLAS material), is open on both ends and has an internal diameter of 1.905 cm. The bottom of each predrilled hole is fitted with a small O-ring to prevent leakage of the water. A 400 microliter aliquot of water (rather than the 250 microliter aliquot used in the Standard Test) with a resistance of 17 mega Ohms is then placed in the hole to cover the test sample. This will normally result in a liquid height for water of about 1.4 mm. The Elsnau probe is positioned through the drilled hole so that the bottom of the probe rests on the bottom of the well at a right angle. Because of the fixed shape, data can be obtained as conductance in micro Siemens/cm/ml using the method described for calculation.
As will be appreciated by those skilled in the art, a variety of other shapes, sizes and orientations of electrodes can be used. In another variation on the Fixed Geometry Test, thin gold wires (99% purity, set of 2, each about 1 mm in diameter) can be constructed to be in parallel with the surface of the water (and covered by the water) and conductance can be measured.
The electrode used in both types of tests must be calibrated so that a conductivity in micro Siemens can be obtained. Such calibration with a salt solutions in water of known conductance is known to those skilled in the art.
While different readings can be obtained depending on the thickness of the films, the test used, etc. it is important to establish a standard test for purposes of defining conductivity according to this invention. The Fixed Geometry Test is set as the defining test because it is believed to be more reproducible. Thus a minimum conductance value of 250 micro Siemens/cm/ml is the lower limit. Interestingly, minimum values for the Standard Test seemed to run about 400 micro Siemens due to the way the test was conducted. For the data described here, samples should be placed in a chamber at the humidity and elevated temperature conditions described above for about 2 hours. Samples not subjected to elevated temperatures should give higher values.
An average efficacy gel having a water content of greater than 35% (such as Gillette""s Right Guard Antiperspirant Gel) was compared with an improved gel made according to Example 12 below. The average efficacy gel has a standard conductivity of 295xc2x135 micro Siemens at 10 seconds and a fixed geometry conductivity of 121xc2x147 micro Siemens/cm/ml at 10 seconds. The improved formulation made according to this invention (Example 21) had a standard conductivity of 4526 micro Siemens at 10 seconds. The improved formulation was ranked as above average in efficacy in a forearm test whereas the average gel was ranked as average in efficacy in a clinical test.
It is believed that the more homogeneous the composition is and the more uniform the particle size, the better properties of the composition.
Throughout the present specification, where compositions are described as including or comprising specific components or materials, or where methods are described as including or comprising specific steps, it is contemplated by the inventors that the compositions of the present invention also consist essentially of, or consist of, the recited components or materials, and also consist essentially of, or consist of, the recited steps. Accordingly, throughout the present disclosure any described composition of the present invention can consist essentially of, or consist of, the recited components or materials, and any described method of the present invention can consist essentially of, or consist of, the recited steps.